Field of the Disclosure
Embodiments of the disclosure relate to a display device having a touch sensor.
Description of the Related Art
As various electronic devices including home appliances, portable information devices, etc. are becoming more lightweight and slimmer, user input means is being switched from a button switch to a touch sensor. Hence, the electronic device, for example, a display device, that has been recently released, has the touch sensor (or a touch screen).
The touch sensor has been essentially adopted in the portable information devices, such as smart phones, and has gradually been adopted in display devices such as notebook computers, computer monitors, and home appliances. A technology has been recently proposed to embed the touch sensor in a pixel array of a display panel. The touch sensor, to which the technology is applied, is referred to as an in-cell touch sensor.
In the in-cell touch sensor technology, touch sensors may be installed in the display panel without an increase in a thickness of the display panel. The electronic device having the in-cell touch sensor time-divides one frame period into a period (hereinafter, referred to as “a display driving period”) for driving subpixels and a period (hereinafter, referred to as “a touch screen driving period”) for driving the touch sensors, so as to reduce a mutual influence attributable to the coupling between the subpixels and the touch sensors.
In the in-cell touch sensor technology, electrodes connected to the subpixels of the display panel are used as electrodes of the touch sensors. For example, the in-cell touch sensor technology may include a method of dividing a common electrode for supplying a common voltage to pixels of a liquid crystal display and using the divided common electrodes as the electrodes of the touch sensors.
Some of the display devices, to which the in-cell touch sensor technology is applied, have to satisfy a VESA standard. The in-cell touch sensor technology uses an integrated driving circuit, in which a touch screen driving circuit (for example, a readout integrated circuit (ROIC)) is embedded in a data driving circuit, due to its structural characteristics.
In this instance, the integrated driving circuit has to supply the common voltage to the display panel. However, there is a considerable limit to a distance between a flexible printed circuit board (FPCB) and an input terminal of the integrated driving circuit because of a limit of the size attributable to the VESA standard. Because of this, in a related art, predetermined electric power is supplied only to one side of the integrated driving circuit, so as to satisfy an input resistance requirement of the integrated driving circuit.
For this reason, when a predetermined pattern is represented on the display panel, the related art method generates a block dim (indicating a phenomenon in which the screen of the display panel becomes dim on a per block basis) attributable to a deviation of the common voltage and reduces the display quality of the display panel.